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I am a New Zealand registered nurse and nutritionist (Grad Cert Sci: nutrition, Massey Univ). I am a Certified Zone Instructor, and have worked teaching Zone diet principles to hundreds of clients over the last 10 years. More recently after finding that eating Paleo food choices was the "icing on the cake" health wise, I have become a Paleo enthusiast and teacher. Follow me on twitter @juliannejtaylor

Only 8% met the international recommendations, not exceeding any of these indices.

Almost all fish oil supplements available in the New Zealand market contain concentrations of EPA and DHA considerably lower than claimed by labels. Importantly, the majority of supplements tested exceeded the recommended indices of oxidative markers. Surprisingly, best-before date, cost, country of origin, and exclusivity were all poor markers of supplement quality.

Here is a graph showing the missing Omega 3 EPA and DHA

These graphs show the oxidation levels in the fish oil capsules. Total oxidation values (Totox)

This is unacceptable. There has been criticism of this study, for example methods of testing oxidation were questioned. You can read more here:

How do you ensure omega 3 fish oil is free from oxidation?

Eating fresh fish is one way to be sure you don’t consume omega 3 that is oxidised. The other is to buy fish oil which is tested to a high level, batch tested AFTER it has been encapsulated. This is important, as the process of moving the liquid fish oil into capsules can cause it to become oxidised.

The omega 3 I sell to New Zealanders is Zone OmegaRx. It is tested to the highest standards, IFOS, and every batch of capsules is tested after it has been encapsulated. It is tested for purity, strength and oxidation levels.

Our clients repeatedly say – they notice the difference between this product and others off the shelf – a noticeable reduction in inflammation, improved skin, a boost in energy and better mental focus are typical results.

Fish oil study: Here is the full table of results FYI – we do not know what brand each fish oil actually is.

Table 1: List of retail fish oils tested. Adj, adjusted for labelled n-3 PUFA content to reflect the oxidation products per 300 mg combined EPA + DHA; AV, anisidine value; BBD, time to best before date as per label; PV, peroxide value; RRP, recommended retail price in US dollars per gram of fish oil (equivalent to one capsule in most cases); Totox, total oxidation value. Note: the country of origin reflects the country claimed on the product packaging or by a company representative. It reflects the site of encapsulation or packaging; the vast majority of oils were sourced from South American deep sea fish. International guidelines recommend values for PV, AV, and Totox of <5 meq/l, <20, and <26, respectively

Paleo & Zone Nutrition(NZ)

I am a New Zealand registered nurse and associate registered nutritionist (PGDipSci: nutrition, Massey Univ). I discovered by chance that dietary changes improved my health, reduced the effect of auto-immune issues and enabled me to keep a healthy weight. As a result, I went back to university study nutrition after a 10-year career in design. My post-grad research looked at diet and its effect on rheumatoid arthritis. I am also a researcher for Nigel Latta "Is Sugar The New Fat?" and Simon Gault "Why Are We Fat?" I like powerlifting. Follow me on twitter @juliannejtaylor